Apparatus and method for communicating uplink signaling information

ABSTRACT

A User Equipment, UE, of a cellular communication system transmits scheduling assistance data to a base station comprising a base station scheduler which schedules uplink packet data. The scheduling assistance data relates to uplink packet data transmission from the UE. The UE comprises a channel controller which is operable to cause the scheduling assistance data to be transmitted from the UE to the base station in a first physical resource of an uplink air interface. The first physical resource is not managed by the base station based scheduler. The scheduling assistance data may specifically be transmitted in a first transport channel multiplexed with other transport channels on a physical resource. The transport channels may be individually optimized and may have different termination points and transmission reliabilities. Specifically, the transport channel supporting the scheduling assistance data signaling may have a high reliability and be terminated in the base station.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.12/755,775, filed Apr. 7, 2010, which is a continuation of U.S.application patent Ser. No. 7,701,901, filed Sep. 30, 2005, which claimsthe benefit of United Kingdom application GB 0508799.4, filed May 3,2005, the contents of each of which are incorporated herein byreference.

The invention relates to a signaling of scheduling assistance data in acellular communication system and in particular, but not exclusively, tosignaling in a 3^(rd) Generation Partnership Project (3GPP) cellularcommunication system.

BACKGROUND ART

Currently, 3rd generation cellular communication systems are beingrolled out to further enhance the communication services provided tomobile users. The most widely adopted 3rd generation communicationsystems are based on Code Division Multiple Access (CDMA) and FrequencyDivision Duplex (FDD) or Time Division Duplex (TDD). In CDMA systems,user separation is obtained by allocating different spreading and/orscrambling codes to different users on the same carrier frequency and inthe same time intervals. In TDD user separation is achieved by assigningdifferent time slots to different users in a similar way to TDMA.However, in contrast to TDMA, TDD provides for the same carrierfrequency to be used for both uplink and downlink transmissions. Anexample of a communication system using this principle is the UniversalMobile Telecommunication System (UMTS). Further description of CDMA andspecifically of the Wideband CDMA (WCDMA) mode of UMTS can be found in‘WCDMA for UMTS’, Harri Holma (editor), Antti Toskala (Editor), Wiley &Sons, 2001, ISBN 0471486876.

In order to provide enhanced communication services, the 3rd generationcellular communication systems are designed for a variety of differentservices including packet based data communication. Likewise, existing2^(nd) generation cellular communication systems, such as the GlobalSystem for Mobile communications (GSM) have been enhanced to support anincreasing number of different services. One such enhancement is theGeneral Packet Radio System (GPRS), which is a system developed forenabling packet data based communication in a GSM communication system.Packet data communication is particularly suited for data services whichhave a dynamically varying communication requirement such as for exampleInternet access services.

For cellular mobile communication systems in which the traffic andservices have a non-constant data rate, it is efficient to dynamicallyshare radio resources amongst users in accordance with their needs at aparticular instant. This is in contrast to services with constant datarates, where radio resources appropriate for the service data rate canbe assigned on a long-term basis such as for the duration of the call.

In the current UMTS TDD standards, uplink shared radio resources may bedynamically assigned (scheduled) by a scheduler in a Radio NetworkController (RNC). However, in order to operate efficiently, thescheduler needs to have knowledge of the volume of uplink data which iswaiting for uplink transmission at the individual mobile users. Thisallows the scheduler to assign resources to users who need them most andin particular prevents that resource is wasted by being assigned tomobile stations that do not have any data to send.

A further aspect of efficient scheduling is the consideration of userradio channel conditions. A user for whom the radio path gain to anothercell is similar to the radio path gain to the current serving cell maycause significant interference in the other cell. It can be shown thatsystem efficiency may be significantly improved if the scheduler takesinto account the relative path gains from the user to each cell in theparticular locale of the network. In such schemes, the power oftransmissions by users for whom the path gain to one or more non-servingcells is of similar magnitude to the path gain to the current servingcell is restricted such that the inter-cell interference caused iscontrolled and managed. Conversely, the transmit power of transmissionsby users for whom the path gain to the serving cell is far greater thanthat to other cells is relatively less restricted since the inter-cellinterference caused by such users per unit of transmission power isless.

In practical systems, both the radio conditions and the pending datavolume status may change very rapidly. In order to optimize systemefficiency as these changes occur, it is important that the scheduler inthe network is informed of the very latest conditions such that timelyadjustment of the scheduler operation may be effected.

For example, during a typical active session, there will be periodicspurts of uplink data to send (for example when sending an email,sending completed Internet forms, or when sending TCP acknowledgementsfor a corresponding downlink transfer, such as a web page). These shortdata spurts are known as packet calls, and their duration may span fromtypically a few milliseconds to a few seconds. During a packet call,uplink resources are being frequently allocated and it is efficient forthe buffer volume and radio channel information to be piggybacked onthese uplink transmissions to continually update the scheduler as to thedata sending needs of the user. However, once the packet call hascompleted (all data to send has been sent and the transmission buffer istemporarily empty), allocation of uplink resources is suspended. In thissituation, means for informing the scheduler of the arrival of new data(at the start of a new packet call) must be found. It is important tominimize any delay in this signaling since this contributes directly tothe user-perceived transmission speed.

Release 99 of the Technical Specifications for 3GPP UMTS TDD, define alayer 3 message termed the PUSCH (Physical Uplink Shared Channel)Capacity Request (PCR) message. The logical channel carrying PCR (termedthe Shared Channel Control Channel—SHCCH) may be routed to differenttransport channels depending on the presence of available resources. Forexample, the PCR message may be sent on the Random Access CHannel (RACH)which is terminated within the RNC. As another example, if the resourcesare available, the PCR may also in some cases be sent on the UplinkShared CHannel (USCH).

However, although this approach is suitable for many applications it isnot optimal for many other applications. For example, the definedsignaling is aimed at providing scheduling information to RNC basedschedulers and is designed for this application, and is in particulardesigned with a dynamic performance and delay suited for this purpose.Specifically, the signaling is relatively slow and the allocationresponse by the RNC scheduler is not particularly fast due to the delaysassociated with communication between the base station and the RNC (overthe Lib interface) and the protocol stack delay in receiving the PCR andtransmitting the allocation grant message via peer-to-peer layer 3signaling.

Recently, significant effort has been invested in improving uplinkperformance for 3GPP systems. One way to do this is to move thescheduling entity out of the RNC and into the base stations such thattransmission and retransmission latencies may be reduced. As a result, amuch faster and more efficient scheduling can be achieved. This in turnincreases perceived end-user throughput. In such an implementation, ascheduler located in the base station (rather than in the RNC) assumescontrol over the granting of uplink resources. Fast scheduling responseto user's traffic needs and channel conditions is desirable in improvingthe efficiency of the scheduling and the transmission delays for theindividual UEs.

However, as the efficiency of the scheduling activity relies onsufficient information being available, the requirements for thesignaling functionality become increasingly severe. Specifically, theexisting approach wherein signaling is transmitted to the RNC by layer 3signaling, is inefficient and introduces delays which limit thescheduling performance of a base station based scheduler. In particular,using techniques identical to the prior art (such as the use of PCRmessages) are not attractive due to the fact that the transport channelsused are terminated in the RNC—the signaling information thus ends up ina different network entity than that in which the scheduler resides andan additional delay is introduced in communicating this to the basestation scheduler.

For example, in a 3GPP TDD system, timely updates on radio channelconditions are especially important due to the fact that the uplink anddownlink radio channels are reciprocal. As such, if the user is able toinform the network scheduler of the very latest channel conditions (ase.g. measured on the downlink), and the scheduler is able to respondwith minimal delay, then the scheduler may exploit the reciprocity andassume that the radio channel conditions will be relatively unchanged bythe time an uplink transmission is scheduled and transmitted. Thechannel conditions that may be reported by a mobile station may includethe channel conditions for the cell of the scheduler but may alsoinclude channel conditions relating to other cells thereby allowing afast and efficient scheduling taking into account the instantaneousconditions for other cells and the resulting intercell interferencecaused.

As another example, in 3GPP FDD systems, mobile station buffer volumestatus is signalled within the uplink transmissions themselves. The datais contained within the same Protocol Data Unit (PDU) as the otheruplink payload data—specifically in the MAC-e PDU header. However, thismeans that the signaling information is dependent on the performance andcharacteristics of the uplink data transmissions themselves.

It should also be noted that in this particular method of transmittingsignaling data, the signaling data and user data are multiplexedtogether before forward error correction is applied and consequentlyboth information streams have the same transmission reliabilities. Thus,when retransmissions are required for the (MAC-e) PDU this affects boththe signaling and user data and thus introduces an additional delay forthe signaling. Furthermore, data retransmissions are commonplace foruplink systems where hybrid and fast retransmission schemes are usedbecause the optimum link efficiency (in terms of the energy required pererror-free transmitted bit) is achieved when the probability of errorfor first-time transmissions is relatively high (e.g. 10% to 50%). Thus,uplink signaling techniques adopted for 3GPP FDD uplink suffer fromlatencies which, if applied to a TDD uplink system, may significantlydegrade the, performance of that TDD system with respect to the level ofperformance that is achievable.

Hence, an improved signaling in a cellular communication system would beadvantageous and in particular a system allowing increased flexibility,reduced signaling delay, improved scheduling, suitability for basestation based scheduling and/or improved performance would beadvantageous.

SUMMARY OF THE INVENTION

Accordingly, the Invention seeks to preferably mitigate, alleviate oreliminate one or more of the abovementioned disadvantages singly or inany combination.

According to a first aspect of the invention there is provided anapparatus for transmitting uplink signaling information in a cellularcommunication system; the apparatus comprising: means for generatingscheduling assistance data for a base station based scheduler, thescheduling assistance data relating to uplink packet data transmissionfrom a User Equipment, UE; means for transmitting the schedulingassistance data from the UE in a first physical resource of an uplinkair interface; wherein the first physical resource is not managed by thebase station based scheduler.

The invention may allow improved scheduling by a base station basedscheduler resulting in an improved performance of the cellularcommunication system as a whole. The invention may allow improvedperformance as perceived by the end-users. The invention may e.g.provide increased capacity, reduced delays and/or increased effectivethroughput. The invention may allow a flexible signaling and may allowthe scheduling assistance data to be provided with short delays. Theinvention may in particular provide for signaling of schedulingassistance data which is particularly suitable for a scheduler based ina base station.

The data on the first physical resource is not scheduled by the basestation based scheduler. Rather the data on the first physical resourcemay for example be scheduled by a scheduler of the RNC supporting thebase station of the base station based scheduler. The first physicalresource may be a resource which the base station based scheduler doesnot have any controlling relationship with and/or information of. Aphysical resource may for example be a group of one or more physicalchannels of the cellular communication system. The uplink packet datatransmissions of the UE may be for a shared uplink packet data serviceand/or channel.

The apparatus for receiving uplink signaling information may be the UserEquipment.

According to an optional feature of the invention, the means fortransmitting is arranged to transmit the scheduling assistance data on afirst transport channel supported by the first physical resource.

This may allow an efficient implementation and may provide compatibilitywith many existing cellular communication systems.

According to an optional feature of the invention, the first transportchannel is a base station terminated transport channel terminated in abase station of the base station based scheduler.

This may allow improved scheduling and may in particular allow a fasterand lower complexity signaling of scheduling assistance data. Inparticular, in existing cellular communication systems, a new transportchannel may be introduced which is particularly suitable for schedulingperformed at a base station.

According to an optional feature of the invention, the means fortransmitting is arranged to transmit other data on a second transportchannel multiplexed on to the first physical resource with the firsttransport channel.

This may allow increased flexibility, efficiency and/or performance. Thefeature may allow a practical use of physical resources and may allow anefficient signaling of the scheduling assistance data using a physicalresource that may be used for other purposes. Additionally oralternatively, it may allow an optimization of the transmissioncharacteristics for the scheduling assistance data with reducedrestrictions imposed by the requirements for the transmission of theother data.

According to an optional feature of the invention, the first transportchannel has a different termination point than the second transportchannel.

The first transport channel may be terminated in a different networkentity than the second transport channel. For example, the firsttransport channel may be terminated at the base station while the secondtransport channel is terminated at an RNC. The feature may allow aparticularly suitable signaling system and may allow faster signaling ofscheduling assistance data and thus improved scheduling while allowingefficient sharing of resources with other communications managed from adifferent location.

According to an optional feature of the invention, the second transportchannel employs a retransmission scheme and the first transport channeldoes not employ a retransmission scheme.

This may allow improved performance and may in particular allowefficient communication of other data while ensuring fast transmissionfor the scheduling assistance data.

According to an optional feature of the invention, the first transportchannel is encoded in accordance with a first transmission scheme andthe second transport channel is encoded in accordance with a differentsecond transmission scheme.

The first and second transport channels may be transmitted withdifferent transmission reliabilities such that the error rates aredifferent for the scheduling assistance data and the other uplink data.This may in particular allow efficient scheduling by reducing delaywhile allowing an efficient air interface resource usage for other data.

According to an optional feature of the invention, the firsttransmission scheme and the second transmission scheme comprisedifferent error correcting characteristics.

This may allow improved performance and a practical implementation.

According to an optional feature of the invention, the means fortransmitting is arranged to perform rate matching of the first transportchannel and the second transport channel.

The rate matching may be performed in order to adjust the errorcorrecting capability of the first and second transport channels. Thismay allow improved performance and a practical implementation.

According to an optional feature of the invention, the apparatus furthercomprises means for transmitting the scheduling assistance data using asecond physical resource and selection means for selecting between thefirst physical resource and the second physical resource.

This may improve performance and may allow a communication of thescheduling assistance data which is particularly suitable for thecurrent conditions and the current characteristics of the physicalresources. For example, in a 3GPP system, the apparatus may selectbetween a physical random access channel (e.g. PRACH), a dedicatedphysical channel (e.g. DPCH) and/or an uplink channel scheduled by thebase station based scheduler.

According to an optional feature of the invention, the selection meansis arranged to select between the first physical resource and the secondphysical resource in response to an availability of the first physicalresource and the second physical resource.

This may allow efficient signaling and may for example allow schedulingassistance data to be communicated on currently available resources thusallowing a dynamic system wherein the scheduling assistance data iscommunicated on different resources as and when they are available. Suchan arrangement may in particular allow the signaling delay to besubstantially reduced. For example, in a 3GPP system, the apparatus mayselect between a random access physical channel (e.g. PRACH), adedicated physical channel (e.g. DPCH) and/or an uplink channelscheduled by the base station based scheduler depending on which ofthese channels are currently set up. The availability may for example bea duration since the physical resource was available.

According to an optional feature of the invention, the selection meansis arranged to select between the first physical resource and the secondphysical resource in response to a traffic loading of the first physicalresource and the second physical resource.

This may allow efficient signaling and may for example allow schedulingassistance data to be communicated on physical resources that haveexcess capacity. For example, in a 3GPP system, the apparatus may selectbetween a physical random access channel (e.g. PRACH), a dedicatedphysical channel (e.g. DPCH) and/or an uplink channel scheduled by thebase station based scheduler depending on which of these channels havespare capacity.

According to an optional feature of the invention, the selection meansis arranged to select between the first physical resource and the secondphysical resource in response to a latency characteristic associatedwith the first physical resource and the second physical resource.

This may allow efficient signaling and may for example allow schedulingassistance data to be communicated on the physical resource that resultsin the lowest delay for the scheduling assistance data. This may provideimproved performance and scheduling due to reduced delay. The latencycharacteristic may e.g. be an estimated, assumed or calculated delay fortransmission of the scheduling assistance data on each physicalresource.

According to an optional feature of the invention, the second physicalresource is a physical resource managed by the base station basedscheduler.

The second physical resource may support data which is scheduled by thebase station based scheduler. The second physical resource mayspecifically support a user data channel for which the base stationbased scheduler schedules the information. For example, in a 3GPPsystem, the apparatus may select between a physical random accesschannel (e.g. PRACH), a dedicated physical channel (e.g. DPCH)controlled by an RNC scheduler and/or a packet data uplink channel whichis scheduled by the base station based scheduler.

According to an optional feature of the invention, the first physicalresource is associated with a first transport channel and the secondphysical resource is associated with a second transport channel and theselection means is arranged to allocate the scheduling assistance databy associating the scheduling assistance data with the first or secondtransport channel.

This may provide a highly advantageous approach and may in particularallow an efficient selection of the appropriate physical resource whileallowing individual optimisation of transmission characteristics for thescheduling assistance data. The transport channels may be selected inresponse to characteristics associated with the physical resource of thetransport channel.

According to an optional feature of the invention, the first physicalresource is a random access channel. The random access channel mayprovide a particularly suitable channel as it may be used when no otherphysical channels are available. The invention may allow schedulingassistance data for a base station based scheduler to be signaled on arandom access channel which is not controlled by the base station basedscheduler but e.g. by an RNC based scheduler.

According to an optional feature of the invention, the schedulingassistance data comprises an indication of an amount of data pendingtransmission and/or an indication of air interface channel conditionsfor the UE. The scheduling assistance data may alternatively oradditionally e.g. comprise an indication of a relative transmit power ofan uplink transmission of the UE and/or an indication of a user identityassociated with the UE. Such information may allow a particularlyadvantageous scheduling.

According to an optional feature of the invention, the cellularcommunication system is a 3^(rd) Gen eration Partnership Project, 3GPP,system. The 3GPP system may specifically be a UMTS cellularcommunication system. The invention may allow improved performance in a3GPP cellular communication system.

According to an optional feature of the invention, the cellularcommunication system is a Time Division Duplex system. The invention mayallow improved performance in a TDD cellular communication system andmay in particular allow improved scheduling by exploiting the improvedsignaling of channel condition information applicable to both uplink anddownlink channels.

According to a second aspect of the invention there is provided anapparatus for receiving uplink signaling information in a cellularcommunication system; the apparatus comprising: means for receivingscheduling assistance data for a base station based scheduler from theUE in a first physical resource of an uplink air interface, thescheduling assistance data relating to uplink packet data transmissionfrom the User Equipment; wherein the first physical resource is notmanaged by the base station based scheduler.

It will be appreciated that the optional features, comments and/oradvantages described above with reference to the apparatus fortransmitting uplink signaling information apply equally well to theapparatus for receiving uplink signaling information and that theoptional features may be included in the apparatus for receiving uplinksignaling information individually or in any combination.

The apparatus for receiving uplink signaling information may be a basestation.

According to a third aspect of the invention there is provided a methodof transmitting uplink signaling information in a cellular communicationsystem; the method comprising: generating scheduling assistance data fora base station based scheduler, the scheduling assistance data relatingto uplink packet data transmission from a User Equipment, UE;transmitting the scheduling assistance data from the UE in a firstphysical resource of an uplink air interface; wherein the first physicalresource is not managed by the base station based scheduler.

It will be appreciated that the optional features comments and/oradvantages described above with reference to the apparatus fortransmitting uplink signaling information apply equally well to themethod for transmitting uplink signaling information and that theoptional features may be included in the method for transmitting uplinksignaling information individually or in any combination.

For example, in accordance with an optional feature of the invention,the scheduling assistance data is transmitted on a first transportchannel supported by the first physical resource.

As another example, in accordance with an optional feature of theinvention, the first transport channel is terminated in a base stationof the base station based scheduler.

As another example, in accordance with an optional feature of theinvention, the method further comprises transmitting other data on asecond transport channel multiplexed on to the first physical resourcewith the first transport channel.

As another example, in accordance with an optional feature of theinvention, the first transport channel is encoded in accordance with afirst transmission scheme and the second transport channel is encoded inaccordance with a different second transmission scheme.

As another example, in accordance with an optional feature of theinvention, the method further comprises transmitting the schedulingassistance data using a second physical resource and selecting betweenthe first physical resource and the second physical resource.

As another example, in accordance with an optional feature of theinvention, the second physical resource is a physical resource managedby the base station based scheduler.

As another example, in accordance with an optional feature of theinvention, the first physical resource is a random access channel

According to a fourth aspect of the invention there is provided a methodof receiving uplink signaling information in a cellular communicationsystem; the method comprising: receiving scheduling assistance data fora base station based scheduler from the UE in a first physical resourceof an uplink air interface, the scheduling assistance data relating touplink packet data transmission from the User Equipment; wherein thefirst physical resource is not managed by the base station basedscheduler.

It will be appreciated that the optional features comments and/oradvantages described above with reference to the apparatus fortransmitting uplink signaling information apply equally well to themethod for receiving uplink signaling information and that the optionalfeatures may be included in the method for receiving uplink signalinginformation individually or in any combination.

These and other aspects, features and advantages of the invention willbe apparent from and elucidated with reference to the embodiment(s)described hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention will be described, by way of example only,with reference to the drawings, in which

FIG. 1 illustrates an example of a cellular communication system 100 inwhich embodiments of the invention may be employed;

FIG. 2 illustrates a UE, an RNC and a base station in accordance withsome embodiments of the invention;

FIG. 3.a illustrates an example of the switching of a single transportchannel between uplink physical resource types;

FIG. 3.b illustrates an example of the switching of the signalinginformation stream into two or more transport channels each of which hasa fixed association with a physical resource type; and

FIG. 4 illustrates and example of a signaling system in accordance withsome embodiments of the invention.

DETAILED DESCRIPTION OF THE INVENTION

The following description focuses on embodiments of the inventionapplicable to a UMTS (Universal Mobile Telecommunication System)cellular communication system and in particular to a UMTS TerrestrialRadio Access Network (UTRAN) operating in a Time Division Duplex (TDD)mode. However, it will be appreciated that the invention is not limitedto this application but may be applied to many other cellularcommunication systems including for example a GSM (Global System forMobile communication system) cellular communication system.

FIG. 1 illustrates an example of a cellular communication system 100 inwhich embodiments of the invention may be employed.

In a cellular communication system, a geographical region is dividedinto a number of cells each of which is served by a base station. Thebase stations are interconnected by a fixed network which cancommunicate data between the base stations. A mobile station is servedvia a radio communication link by the base station of the cell withinwhich the mobile station is situated.

As a mobile station moves, it may move from the coverage of one basestation to the coverage of another, i.e. from one cell to another. Asthe mobile station moves towards a base station, it enters a region ofoverlapping coverage of two base stations and within this overlap regionit changes to be supported by the new base station. As the mobilestation moves further into the new cell, it continues to be supported bythe new base station. This is known as a

A typical cellular communication system extends coverage over typicallyan entire country and comprises hundreds or even thousands of cellssupporting thousands or even millions of mobile stations. Communicationfrom a mobile station to a base station is known as uplink, andcommunication from a base station to a mobile station is known asdownlink.

In the example of FIG. 1, a first User Equipment (UE) 101 and a secondUE 103 are in a first cell supported by a base station 105. A UE may befor example a remote unit, a mobile station, a communication terminal, apersonal digital assistant, a laptop computer, an embedded communicationprocessor or any communication element communicating over the airinterface of the cellular communication system.

The base station 105 is coupled to an RNC 107. An RNC performs many ofthe control functions related to the air interface including radioresource management and routing of data to and from appropriate basestations.

The RNC 107 is coupled to a core network 109. A core networkinterconnects RNCs and is operable to route data between any two RNCs,thereby enabling a remote unit in a cell to communicate with a remoteunit in any other cell. In addition, a core network comprises gatewayfunctions for interconnecting to external networks such as the PublicSwitched Telephone Network (PSTN), thereby allowing mobile stations tocommunicate with landline telephones and other communication terminalsconnected by a landline. Furthermore, the core network comprises much ofthe functionality required for managing a conventional cellularcommunication network including functionality for routing data,admission control, resource allocation, subscriber billing, mobilestation authentication etc.

It will be appreciated that for clarity and brevity only the specificelements of the cellular communication system required for thedescription of some embodiments of the invention are shown, and that thecellular communication may comprise many other elements including otherbase stations and RNCs as well as other network entities such as SGSNs,GGSNs, HLRs, VLRs etc.

Conventionally, the scheduling of data over the air interface isperformed by the RNC. However, recently packet data services have beenproposed which seek to exploit the fluctuating channel conditions whenscheduling data over a shared channel. Specifically, a High SpeedDownlink Packet Access (HSDPA) service is currently being standardisedby 3GPP. HSDPA allows scheduling to be performed taken the conditionsfor the individual UEs into account. Thus, data may be scheduled for UEswhen channel propagations allow for this to be communicated with lowresource usage. However, in order to enable this scheduling to besufficiently fast to follow the dynamic variations, HSDPA requires thatthe scheduling is performed at the base station rather than by the RNC.Locating a scheduling function in the base station eliminates therequirement for communication over the base station to RNC interface(the Iub interface) thereby reducing the significant delays associatedtherewith.

In order for the scheduling to be efficient, the base station schedulerneeds current information of the channel conditions. Accordingly, in aTDD HSDPA system, the mobile station provides information bytransmitting this information to the base station using a channel whichis controlled by the downlink scheduler. Uplink resources (denotedHS-SICH) are implicitly assigned when the UE receives an allocation fordownlink HSDPA data, such that a positive or negative acknowledgement ofthat downlink data may be returned to the base station based downlinkscheduler. In addition to transmitting the acknowledgement informationon the implicitly-assigned uplink physical resources, the UE alsoincludes current information of the channel conditions. Thus,information is transmitted to the scheduler on the HS-SICH which is setup and controlled by the scheduler controlling the HSDPA communication.

It has recently been proposed to introduce an uplink packet data servicesimilar to HSDPA. In particular, such a service would utilise a basestation based scheduler to schedule user data on an uplink packetchannel. However, in order for such a system to operate efficiently itis necessary that the scheduler is provided with information from the UEwith a minimum of delay. It has been proposed to provide thisinformation by including the information with the uplink user data.Specifically, it has been proposed to piggyback the data on the useddata packets by including such data in the MAC-e header of the uplinkuser data PDUs (Packet Data Units).

However, a solution where the signaling data is transmitted on aphysical resource for which data is scheduled by the base stationscheduler is suboptimal in many situations. In particular, it leads toan inflexible system and restricts the possible scheduling as thescheduler must also ensure that data packets are transmittedsufficiently often to allow the signaling information to be transmitted.Thus, whereas the solution may be practical in scenarios where there aresufficiently frequent uplink transmissions, it is not suitable forscenarios where UEs do not transmit packet data during relatively longintervals.

FIG. 2 illustrates the UE 101, the RNC 107 and the base station 105 ofthe example of FIG. 1 in more detail. In the example, the RNC 107comprises an RNC scheduler 201 which is responsible for schedulingconventional 3GPP physical channels such as for example a DedicatedPhysical CHannel (DPCH) as will be known to the person skilled in theart. Thus, the RNC scheduler 201 schedules data for communication overthe air interface as defined in Release 99 of the 3GPP technicalspecifications.

In the example of FIG. 2, the base station 105 comprises an RNCinterface 203 which is responsible for communicating with the RNC 107over the Iub interface. The RNC interface 203 is coupled to a basestation controller 205 which controls the operation of the base station105. The base station controller 205 is coupled to a transceiver 207which is operable to communicate with the UE 101 over the air interface.The base station controller 205 performs all the functionality requiredfor transmitting data received from the RNC 107 to the UE 101 as well asfor receiving and forwarding data received from the UE 101 to the RNC107.

The base station 105 furthermore comprises a base station scheduler 209which is coupled to the base station controller 205. The base stationscheduler 209 is responsible for scheduling data for an uplink sharedpacket data service. Specifically, the base station scheduler 209schedules user data on a shared transport channel of a shared physicalresource and generates resource allocation information for the sharedphysical resource. The allocation information is fed to the base stationscheduler 209 and transmitted to the UEs 101, 103 over the airinterface.

As the base station scheduler 209 is located in the base station 105, itcan schedule data without the additional delay required forcommunication of allocation information over the Iub interface (asrequired for the RNC scheduler 201).

The base station scheduler 209 schedules data for the uplink transportchannel based on different information. In particular, the base stationscheduler 209 may schedule data in response to the individual airinterface channel propagation characteristics and the current transmitbuffer requirements of the UEs. Accordingly, this information ispreferably obtained from scheduling assistance data which is transmittedto the base station 105 from the UEs 101, 103. In order to have anefficient scheduling, the scheduling assistance data is preferablyreceived with low delay and frequent intervals. Accordingly, it isdesirable that the scheduling assistance data is provided to the basestation scheduler 209 without it first being transmitted to and receivedfrom the RNC 107 over the Iub interface.

In the example of FIG. 2, the UE 101 comprises a transceiver 211 whichis operable to communicate with the base station 105 over the airinterface in accordance with the 3GPP Technical Specifications. It willbe appreciated the UE 101 furthermore comprises the required or desiredfunctionality for a UE of a 3GPP cellular communication system.

The UE 101 comprises a channel controller 213 which is operable toallocate data to individual physical resources and transport channelscorresponding to the 3GPP Technical Specifications. For example, the UE101 may be involved in a circuit switched conventional Release 99communication. Thus, the UE may comprise a dedicated data source 215which generates user data to be transmitted to the RNC 107. The channelcontroller 213 is coupled to the dedicated data source 215 and mayallocate the dedicated data to the appropriate channel such as the DCH(Dedicated CHannel). The channel controller 213 may further control thetransmission of this to the base station in the appropriate physicalchannel, such as the DPCH (Dedicated Physical CHannel).

In the example, the UE 101 is furthermore involved in a packet datacommunication. For example, the UE 101 may be involved in an Internetaccess application supported by an uplink packet data service. In theexample of FIG. 1, the UE 101 comprises a packet data transmit buffer217 which stores the packet data until it is scheduled for transmissionover the shared uplink channel. This scheduling is performed by the basestation scheduler 209 rather than by the RNC scheduler 201.

The packet data transmit buffer 217 is coupled to a schedulingassistance data generator 219 which generates scheduling assistance datafor transmission to the base station 105. In particular, the schedulingassistance data relates to information that is available at the UE 101and which may be used by the base station scheduler 209 when schedulingdata.

Specifically for FIG. 2, the scheduling assistance data generator 219 iscoupled to the packet data transmit buffer 217 and obtains dynamicinformation of the current buffer loading from this. Thus, thescheduling assistance data generator 219 determines how much data iscurrently stored in the packet data transmit buffer 217 pendingtransmission over the uplink channel.

The scheduling assistance data generator 219 includes an indication ofthis pending transmit data amount in the scheduling assistance data.Furthermore, the scheduling assistance data generator 219 may beprovided with information which is indicative of the current propagationconditions and may include this information in the scheduling assistancedata. The propagation conditions for the shared physical resource mayfor example be determined from signal level measurements on receivedsignals. In the example of a TDD system, this downlink propagation datamay be considered applicable for the uplink propagation data as wellsince both uplink and downlink use the same frequency.

The scheduling assistance data generator 219 is coupled to the channelcontroller 213 which is arranged to transmit the scheduling assistancedata from the UE 101 in a first physical resource of the uplink airinterface. Thus, the channel controller 213 receives the schedulingassistance data from the scheduling assistance data generator 219 andcauses this to be transmitted to the base station over a physicalresource of the air interface.

In the example of FIG. 2, the channel controller 213 transmits thescheduling assistance data over a physical resource which is not managedby the base station based scheduler. In particular, the channelcontroller 213 selects a physical channel which is controlled by the RNCscheduler 201.

As an example, the channel controller 213 may transmit the schedulingassistance data on a dedicated physical resource used for a circuitswitched voice call. Specifically, the channel controller may piggybackthe scheduling assistance data together with a DPDCH which has been setup and is controlled by the RNC scheduler 201, onto DPCH physicalresources assigned which are again set up and controlled by the RNCscheduler 201. As another example, the channel controller may transmitthe scheduling assistance data on a Random Access CHannel (the PRACHchannel).

When the communication is received at the base station 105, the basestation controller 205 is in the example of FIG. 2 arranged to extractthe scheduling assistance data and to feed it to the base stationscheduler 209. For example, the base station controller 205 may monitorthe DPDCH and/or the PRACH and when it detects that schedulingassistance data is being received, it may decode this data and send itto the base station scheduler 209.

It will be appreciated that in some embodiments, the RNC scheduler 201may specifically allocate segments of the physical resource for thecommunication of scheduling assistance data and information identifyingthese segments may be communicated both to the base station 105 and theUE 101.

The scheduling assistance data is thus in this example received on aphysical resource which is shared by other services supported byscheduling in the RNC. In some embodiments, the scheduling assistancedata may be received on a physical resource which is supported by adifferent scheduler in the base station 105, such as in the case ofHS-SICH for HSDPA. Specifically, these services may be conventionalrelease 99, release 4 or release 5 services. Thus, an efficient andflexible communication of scheduling assistance data is achieved whilemaintaining backwards compatibility and avoiding the requirement of thebase station scheduler 209 needing to allocate resource for schedulingassistance data. Rather, in many situations, unused resource of the RNCscheduled physical resources may be used for communication of schedulingassistance data.

Furthermore, the system of FIG. 2 allows a very fast communication ofscheduling assistance data as the signaling avoids the delay inherent incommunication over the Iub interface between the base station 105 andthe RNC 107.

In the example, the base station scheduler 209 may be provided withscheduling assistance data indicative of the air interface channelconditions and the transmit data requirements of UEs 101, 103 atfrequent intervals (due to the efficient resource utilization) and withvery low delays. This allows a much faster scheduling taking intoaccount fast varying characteristics and thus results in a much improvedscheduling. This leads to an improved resource usage and increasedcapacity of the cellular communication system as a whole.

In the example of FIG. 2, the scheduling assistance data is communicatedon a transport channel. A transport channel may be a channel thatcarries PDUs to and from the physical layer and the MAC layer. Aphysical channel carries bits over the air interface. A physical channelis specifically a Layer 1 (Physical layer) channel. A logical channelcarries PDUs between the MAC layer and the RLC (Radio Link Control)layer.

Specifically, for 3GPP systems, a transport channel is aninformation-bearing interface between a 3GPP Multiple Access Control(MAC) entity, and a 3GPP physical layer entity. A physical channel is aunit of transmission resource, defined in 3GPP as a specific spreadingcode and period of time occupancy on the air interface; a unit oftransmission resource. A logical channel is an information-bearinginterface at the transmission input to the MAC.

In the specific example, the physical resource supports two or moretransport channels which are multiplexed onto the same physicalresource. Specifically, a new transport channel may be defined forcommunication of the scheduling assistance data and this transportchannel may be multiplexed together with one or more DCH(s) onto one ormore physical DPCH channels on which the DCH(s) are carried in a 3GPPsystem.

For a 3GPP system, two or more separate information streams may bemultiplexed onto a common set of physical resources in several ways:

Physical Layer Field Multiplexing

For physical layer field multiplexing, the multiple information streamsare separately encoded (if required) and occupy mutually exclusive (andusually contiguous) portions of the transmission payload.De-multiplexing is achieved by extracting the relevant portions of thetransmission payload for each stream and treating them independentlythereafter.

Transport Channel Multiplexing

For transport channel multiplexing, the multiple information streams areseparately encoded and a coordinated rate matching scheme is applied toeach stream such that the total number of bits after rate matchingexactly fits the transmission payload. Generally, this is similar tophysical layer multiplexing except that the bits corresponding to eachinformation stream are usually non-contiguous in the final transmissionpayload. Additionally, the rate matching scheme is designed in such away that the amount of FEC applied to each stream may be varied in aflexible manner, allowing for various and differing quality requirementsto be met independently for each stream. De-multiplexing is enabled viathe receiver having knowledge of the rate matching scheme algorithmapplied in the transmitter.

Logical Channel Multiplexing

For logical channel multiplexing, the multiple information streams aremultiplexed by the MAC layer prior to forward error correction encodingby the physical layer, with a header being applied to each stream toenable de-multiplexing in the receiver. FEC encoding is applied to thecomposite (multiplexed) stream, and so each stream will experience thesame transmission reliability.

It will be appreciated that although the physical resource, such as theDPCH channel, is controlled by the RNC scheduler, the transport channelused for the scheduling assistance data is preferably terminated at thebase station 105 while the dedicated transport channel, the DCH, isterminated at the RNC 107. Thus, although the transport channel used forthe scheduling assistance data and the transport channel used for otherdata are multiplexed onto the same physical resource, they terminate indifferent entities. This may allow a particularly efficient and flexiblesignaling and may in particular minimize the delay for the schedulingassistance data. Specifically, it may avoid the delay associated withreceiving the scheduling assistance data on a RNC terminated transportchannel and retransmitting this to the base station 105.

It will be appreciated that the different physical resources controlledby the RNC 107 may be used to support the communication of thescheduling assistance data.

For example, as described, a DPCH or PRACH physical channel may be used.In some embodiments, the UE 101 and base station 105 may additionallycomprise functionality for communicating the scheduling assistance dataon a physical resource which is managed by the base station scheduler209. Thus, in this example, the UE 101 may comprise functionality forcommunicating on a number of different physical resources. In theexample of FIG. 2, a suitable physical resource on which to communicatethe scheduling assistance data may be selected depending on the currentconditions and operating environment and a suitable physical channel maybe selected to provide the best performance for the current conditions.

Thus, in this example the signaling used to assist the enhanced uplinkscheduling process by the base station scheduler 209 is intelligentlyrouted and transmitted on different uplink physical resources accordingto the current preferences and conditions. In particular, a physicalresource may be selected based on the presence or absence of thoseuplink physical resources. The scheduling assistance data mayfurthermore be communicated in a transport channel which is terminatedin the base station 105.

In an alternative approach, the signaling used to assist the enhanceduplink scheduling process by the base station scheduler 209 may berouted and transmitted on different transport channels, and hence,physical resources, under the control of the network, via network-to-UEsignaling means.

The intelligent-routing approach will be illustrated with reference toan example where three specific configurations are considered:

Scenario 1:

The user equipment 101 intends to inform the base station scheduler 209about its current packet data transmit buffer status or radioconditions, yet no enhanced uplink resources have been granted fortransmission and no other uplink radio resources are in existence or areavailable. This situation is common when the UE 101 has previouslyfinished transmission of a packet call, has been idle for a period oftime, and new data arrives in the UE's 101 packet data transmit buffer217. The user must then inform the base station scheduler 209 of itsneed for transmission resources to transmit the new data.

Scenario 2:

The user equipment 101 intends to update the base station scheduler 209with new air interface condition information or buffer information andpacket data uplink resources scheduled by the base station scheduler 209are already available. In this case, the UE 101 may piggyback the uplinksignaling using a part of the resources granted for transmission of theuplink packet data transmission itself.

Scenario 3:

The user equipment 101 intends to update the base station scheduler 209with new channel or buffer information, no packet data uplink resourcesmanaged by the base station scheduler 209 are available, yet other RNCmanaged uplink resources are in existence and are available. In thiscase, the UE 101 may piggyback the signaling using a part of theexisting uplink resources.

Thus, in some embodiments the channel controller 213 of the UE 101 andthe base station controller 205 of the base station 105 comprisefunctionality for selecting between different physical resources.Furthermore, this selection may be performed in response to whether thedifferent physical resources are available.

As a specific example, the channel controller 213 may first evaluate ifan uplink packet data channel controlled by the base station scheduler209 is available. If so, this channel is selected for transmission ofthe scheduling assistance data. Otherwise, the channel controller 213may evaluate if an uplink physical channel controlled by the RNCscheduler 201 is set up (such as a DPCH). If so, the schedulingassistance data is transmitted on this channel. However, if no suchchannel is available, the channel controller 213 may continue totransmit the scheduling assistance data using a random access channel(the PRACH).

In different embodiments, the selection of physical resources may bemade in response to different parameters or characteristics. Forexample, the channel controller 213 and base station controller 205 maytake into account parameters such as:

The presence or absence of uplink physical resource types.

The time since an uplink physical resource type was last present. Forexample, a given physical resource may be selected only if it has beenavailable within a given time interval.

The traffic loading of channels mapped to the uplink resource types. Forexample, a physical resource may be selected if the traffic loading isso low that there is spare available resource.

A consideration of the transmission latency of the uplink signaling. Forexample, each physical resource may have an associated latency due tosignaling delays, encoding etc. and the physical resource having thelowest latency may be selected in preference to other physicalresources.

Alternatively or additionally, the selection of the physical resourcemay be performed in response to a configuration by the fixed network andin particular the RNC. For example, some signaling routes may beexplicitly allowed or disallowed by the fixed network.

The selection of physical resources may for example be made by selectinga transport channel ani then selecting a physical resource on which totransmit this transport channel. As another example, the selection ofphysical resources may be made by having different transport channelslinked to different physical channels and then selecting the appropriatetransport channel.

FIG. 3 illustrates the principles between these exemplary switchingembodiments. In particular, FIG. 3 a illustrates an example of theswitching of a single transport channel between uplink physical resourcetypes and FIG. 3.b illustrates an example of the switching of thesignaling information stream into two or more transport channels eachhaving a fixed association with a physical resource type.

In the example of FIG. 3 a, the scheduling assistance data is includedin a new transport channel (TrCH #1). The transport channel is thenswitched either to a first or second transport channel multiplexerdepending on the desired physical resource type. The selected transportchannel multiplexer multiplexes the transport channels with othertransport channels to be communicated on the physical resource.

In the example of FIG. 3 b, the scheduling assistance data is eitherincluded in a first transport channel (TrCH #1) or a second transportchannel (TrCH #2). Each of the transport channels is supported by adifferent physical resource and the selected transport channel ismultiplexed with other transport channels before being transmitted onthe physical resource. The selection of the specific transport channelfor the scheduling assistance data may be made in response tocharacteristics of the physical resources associated with the individualtransport channels.

It will be appreciated that in the specific examples, transport channelmultiplexing has been employed. Multiplexing of the transport channelsprovides a number of advantages and options particularly suitable forthe described embodiments.

For example, in contrast to physical layer multiplexing it enables theuplink signaling to be multiplexed with legacy channels (e.g. Release 99defined channels) without having a large impact on the 3GPP TechnicalSpecifications.

Furthermore, existing approaches for transport channel multiplexingwithin 3GPP may be re-used with minimal impact on the TechnicalSpecifications and thus improved backwards compatibility may beachieved.

Furthermore, usage of transport channel multiplexing may in someembodiments be used to individually optimize performance for theindividual transport channels. In some embodiments, differenttransmission schemes are used for the different transport channels. Inparticular, different transmission schemes resulting in differenttransmission reliability may be used.

As a specific example, the forward error correction coding may beselected individually for each transport channel and for example ahigher reliability forward error correction coding may be selected forthe transport channel carrying the scheduling assistance data than far atransport channel carrying user data. This difference in forward errorcorrection coding may be achieved by using different encoders/decodersor may be achieved by different puncturing or repetition characteristicsbeing applied when performing rate matching.

In particular, one of the transport channels may employ a retransmissionscheme where faulty data packets are retransmitted from the UE 101whereas the other transport channel does not employ a retransmissionscheme but rather transmits the data with a more reliable error coding.Thus, in this example, a single physical resource may comprise a firsttransport channel used for transmission of non-delay-sensitive data. Thetransmissions may have a high data packet error rate of, say, 10-30%resulting in a large number of retransmissions and thus increased delaybut also in a very efficient resource utilization. At the same time, thephysical resource may support a second transport channel used for thetransmission of the scheduling assistance data and this transportchannel may have a very low data rate thus ensuring that the packet datais received reliably and thus minimizing delay resulting in improvedscheduling by the base station scheduler 209.

Furthermore, in some embodiments the transport channels of the physicalresource may be terminated at different points in the fixed network.Specifically, a transport channel may be used for user datacommunication and may be terminated at the RNC 107 while a secondtransport channel is used for communication of the scheduling assistancedata and is terminated in the base station 105. Thus, the same physicalresource may support transport channels which are individuallyterminated at the optimum location. This may reduce delays associatedwith the scheduling assistance data and may improve the schedulingperformance of the base station scheduler 209.

FIG. 4 illustrates an example of a signaling system in accordance withsome embodiments of the invention. The illustrated functionality mayspecifically be implemented in the channel controller 213 of FIG. 2. Theoperation will be described with reference to the three specificexemplary 3GPP UTRAN TDD scenarios previously described.

Scenario 1

In scenario 1, due to the fact that the existing RACH is terminated inthe RNC 107, the base station 105 cannot make use of this transportchannel to carry the necessary uplink signaling. The RACH is not“visible” to the base station 105 and simply passes through it on itsway to the RNC. It would be possible to forward the received informationback from the RNC to the Node-B via new Iub signaling although thistechnique suffers greatly from the latency involved in these multipletransmission legs.

Non-random-access methods may also be considered (such as circularpolling) but such techniques again suffer from potential latencyincreases (there is a potential significant delay between data arrivingin the user's transmission buffer(s) and uplink resources being grantedto serve that data).

In accordance with the example of FIG. 4, a new base station terminatedrandom access channel which is able to convey the scheduling assistancedata directly to the base station scheduler 209 is defined.

The new random access channel is termed “E-SACH_(R)” (Enhanced UplinkScheduler Assistance Channel) in the example of FIG. 4. The “R”subscript relates to the fact that the channel is random access innature (ie: non-scheduled and in particular not scheduled or managed bythe base station scheduler 209). The channel is able to carry anindication to the base station scheduler 209 that new data has arrivedin the user's transmission buffer and is in effect a request for uplinkradio resources. It may also carry an indication of the current channelconditions and, because the transmission is random access, it may alsocarry an indication of the user identity such that the base stationscheduler 209 knows which user to allocate the resources to.

Scenario 2

With the uplink data payload being carried on one transport channelscheduled by the base station scheduler 209 (denoted theEnhanced-Dedicated CHannel-E-DCH), the uplink signaling may be carriedon a separate transport channel (denoted E-SACH_(E) in FIG. 4). LikeE-SACH_(R), E-SACH_(E) is terminated at the base station 105. The “E”subscript is used to denote that the scheduling assistance informationis piggy-backed on the enhanced uplink transmission scheduled by thebase station scheduler 209. However, because it is conveyed on ascheduled transmission, the need to carry the user identity in thesignaling is obviated. Thus, the PDU size of an E-SACH_(E) PDU is likelyto be different to that of an E-SACH_(R) PDU. The two (or more)transport channels are multiplexed onto the same set of physicalresources (termed a CCTrCH). Furthermore, it is possible to adjust thedegree of FEC coding applied to E-SACH_(E) and E-DCH, to optimize thetransmission reliability of each transport channel as desired. Forexample, it may be desirable for the E-SACH_(E) to be given a higherdegree of FEC protection than the E-DCH, such that the schedulerinformation gets to the scheduler with high reliability (usually in asingle transmission) whilst the E-DCH is able to utilize the ARQ(retransmission) efficiencies by operating each transmission instance atoptimum link reliability (often involving multiple transmissions perunit of data before it is received without error).

Scenario 3

This scenario is similar to that of scenario 2, with the key differencebeing that the uplink signaling is piggybacked on uplink resources whichare not directly associated with the enhanced uplink transmission andwhich are not scheduled by the base station scheduler 209. These uplinkresources are here termed “auxiliary”. For example, enhanced packet datauplink may be used in conjunction with the HSDPA downlink packet dataservice. In such a case an associated uplink DCH exists (typically usedto carry higher layer user data such as TCP (Transmit Power Control)acknowledgements, and layer 3 control traffic to control events (such ashandovers). The scheduling assistance data may in such a case betransmitted on uplink DPCH physical resources or on another uplink HSDPAchannel such as the HS-SICH (High Speed—Shared Information Channel).

When no other uplink transmission resources are available, but there isa need to send updated information to the scheduler, it may bepreferable (for latency reasons or to reap efficiency savings) for theuser to piggyback the uplink signaling of scheduling assistance dataonto the auxiliary uplink resources, rather than using the E-SACH_(R)random access procedures.

Again, in order to facilitate control over the degree of forward errorcorrecting coding applied to the auxiliary traffic and the uplinksignaling, and to enable separate detection of each, a separateiransport channel is used for the uplink signaling, termed theE-SACH_(D). As in scenario 2, the E-SACH_(D) is terminated at basestation 105 and is multiplexed together with other data onto a commonset of auxiliary uplink radio resources (the auxiliary uplink CCTrCH).

It will be appreciated that the above description for clarity hasdescribed embodiments of the invention with reference to differentfunctional units and processors. However, it will be apparent that anysuitable distribution of functionality between different functionalunits or processors may be used without detracting from the invention.For example, functionality illustrated to be performed by separateprocessors or controllers may be performed by the same processor orcontrollers. Hence, references to specific functional units are only tobe seen as references to suitable means for providing the describedfunctionality rather than indicative of a strict logical or physicalstructure or organization.

The invention can be implemented in any suitable form includinghardware, software, firmware or any combination of these. The inventionmay optionally be implemented at least partly as computer softwarerunning on one or more data processors and/or digital signal processors.The elements and components of an embodiment of the invention may bephysically, functionally and logically implemented in any suitable way.Indeed the functionality may be implemented in a single unit, in aplurality of units or as part of other functional units. As such, theinvention may be implemented in a single unit or may be physically andfunctionally distributed between different units and processors.

Although the present invention has been described in connection withsome embodiments, it is not intended to be limited to the specific formset forth herein. Rather, the scope of the present invention is limitedonly by the accompanying claims. Additionally, although a feature mayappear to be described in connection with particular embodiments, oneskilled in the art would recognize that various features of thedescribed embodiments may be combined in accordance with the invention.In the claims, the term comprising does not exclude the presence ofother elements or steps.

Furthermore, although individually listed, a plurality of means,elements or method steps may be implemented by e.g. a single unit orprocessor. Additionally, although individual features may be included indifferent claims, these may possibly be advantageously combined, and theinclusion in different claims does not imply that a combination offeatures is not feasible and/or advantageous. Also the inclusion of afeature in one category of claims does not imply a limitation to thiscategory but rather indicates that the feature is equally applicable toother claim categories as appropriate. Furthermore, the order offeatures in the claims do not imply any specific order in which thefeatures must be worked and in particular the order of individual stepsin a method claim does not imply that the steps must be performed inthis order. Rather, the steps may be performed in any suitable order. Inaddition, singular references do not exclude a plurality. Thusreferences to “a”, “an”, “first”, “second” etc do not preclude aplurality.

1. A mobile terminal for transmitting uplink signalling information in acellular communication system, the mobile terminal comprising: ascheduling assistance data generator configured for generatingscheduling assistance data for a base station based scheduler, thescheduling assistance data relating to physical resource allocation foruplink packet data transmission from the mobile terminal; a transmitteroperable to transmit the scheduling assistance data from the mobileterminal in a first physical resource of an uplink air interface andoperable to transmit the scheduling assistance data using a secondphysical resource of the uplink air interface, wherein the firstphysical resource is arranged to provide an identifier of the mobileterminal and is not scheduled by the base station based scheduler andthe second physical resource is an uplink channel operable to conveydata from a layer higher than a physical layer in addition to thescheduling assistance data, wherein the second physical resource isshared amongst a plurality of mobile terminals, and a channel controlleroperable to select between the first physical resource and the secondphysical resource in response to a resource availability of the firstphysical resource and the second physical resource to transmit thescheduling assistance data.
 2. A mobile terminal according to claim 1,wherein the transmitter is configured to transmit the schedulingassistance data on a first channel supported by the first physicalresource.
 3. A mobile terminal according to claim 2, wherein the firstchannel is a base station terminated channel terminated in a basestation of the base station based scheduler.
 4. A mobile terminalaccording to claim 1, wherein the data from a layer higher than thephysical layer has a different termination point than the schedulingassistance data.
 5. A mobile terminal according to claim 1, wherein thedata from a layer higher than the physical layer employs aretransmission scheme and the scheduling assistance data does not employthe retransmission scheme.
 6. A mobile terminal according to claim 1,wherein the data from a layer higher than the physical layer is encodedin accordance with a first transmission scheme and the schedulingassistance data is encoded in accordance with a different secondtransmission scheme.
 7. A mobile terminal according to claim 6, whereinthe first transmission scheme and second transmission scheme comprisedifferent error correcting characteristics.
 8. A mobile terminalaccording to claim 1, wherein the channel controller is configured toselect between the first physical resource and the second physicalresource in response to a lack of resource allocation of either thefirst physical resource or the second physical resource.
 9. A mobileterminal according to claim 1, wherein the channel controller isconfigured to select between the first physical resource and the secondphysical resource in response to a latency characteristic associatedwith the first physical resource and the second physical resource.
 10. Amobile terminal according to claim 1, wherein the first physicalresource is associated with a first channel and the second physicalresource is associated with a second channel and the schedulingassistance data generator is configured to allocate the schedulingassistance data by associating the scheduling assistance data with thefirst or second channel.
 11. A mobile terminal according to claim 3,wherein the first physical resource is a random access channel and thefirst channel is a higher layer channel mapped onto the random accesschannel.
 12. A mobile terminal according to claim 1, wherein thescheduling assistance data comprises an indication of an amount of datapending transmission.
 13. A mobile terminal according to claim 1,wherein the cellular communication system is a Universal MobileTelecommunication System.
 14. A mobile terminal according to claim 1,wherein the data from a layer higher than the physical layer comprisesacknowledgment data for downlink packet data.
 15. A method oftransmitting uplink signalling information in a cellular communicationsystem, the method comprising: generating scheduling assistance data fora base station based scheduler, the scheduling assistance data relatingto physical resource allocation for uplink packet data transmission froma mobile terminal; selecting between a first physical resource and asecond physical resource in response to a resource availabilitycharacteristic of the first physical resource and the second physicalresource, and if the first physical resource is selected, transmittingthe scheduling assistance data from the mobile terminal using the firstphysical resource of an uplink air interface, wherein the first physicalresource is operable to indicate an identifier of the mobile terminaland is not scheduled by the base station based scheduler, and if thesecond physical resource is selected, transmitting the schedulingassistance data from the mobile terminal using the second physicalresource of the uplink air interface, wherein the second physicalresource is an uplink channel operable to convey data from a layerhigher than a physical layer in addition to the scheduling assistancedata, and wherein the second physical resource is shared amongst aplurality of mobile terminals.
 16. A method according to claim 15,wherein transmitting the scheduling assistance data comprisestransmitting the scheduling assistance data on a first channel supportedby the first physical resource.
 17. A method according to claim 16,wherein the first channel is terminated in a base station of the basestation based scheduler.
 18. A method according to claim 15, wherein thedata from a layer higher than the physical layer is encoded inaccordance with a first transmission scheme and the schedulingassistance data is encoded in accordance with a different secondtransmission scheme.
 19. A method according to claim 15, wherein thesecond physical resource is a physical resource managed by the basestation based scheduler.
 20. A method as claimed in claim 15, whereinthe first physical resource is a random access channel and the firstchannel is a higher layer channel mapped onto the random access channel.21. A method according claim 15, wherein the selecting between the firstphysical resource and the second physical resource is in response to atraffic loading of the first physical resource and the second physicalresource.
 22. A method according to claim 15, wherein the selectingbetween the first physical resource and the second physical resource isin response to a lack of resource allocation of either the firstphysical resource or the second physical resource.
 23. A methodaccording to claim 15, wherein the scheduling assistance data comprisesan indication of an amount of data pending transmission.
 24. A methodaccording to claim 15, wherein the cellular communication system is aUniversal Mobile Telecommunication System.
 25. A method according toclaim 15, wherein the data from a layer higher than the physical layercomprises acknowledgment data for downlink packet data.